Method of sealing a container

ABSTRACT

A reclosable container having a removable top closure mechanically joined to the container body to carry the structural loads of container and contents, the mechanical joint being cylindrical and connected and disconnected by rotation of the top closure and the container body relative to each other. The ultimate seal during the shelf-life between filling and initial opening of the container is effected by a rupturable band adhered over the joint, said band in the locus of the joint line having a strength in shear less than its adhesive bond to the container closure and body adjacent the joint line. The closure and body are preferably recessed adjacent the joint line to receive the band. The band is preferably endless and formed in situ by application of band material in liquid condition; a repellent or adhesion inhibiter (preferably an immiscible liquid) may be located in or over the joint line to exclude entrance of the band material into the joint and provide an equatorial area of weakness for rupture of the sealing band.

United States Patent 1 Asmus [45] July 31, 1973 METHOD OF SEALING ACONTAINER [76] Inventor: Richard W. Asmus, 3628 W. 48th St., Cleveland,Ohio 44102 221 Filed: Jan. 25, 1971 211 Appl. No.: 109,560

Related US. Application Data [62] Division of Ser. No. 863,105, Oct. 2,1969, Pat. No.

3,303,761 2/1967 Monroe etal. .93/44.1R

Primary Examiner-Robert L. Spruill AttorneyEly, Golrick & Flynn [5 7]ABSTRACT A reclosable container having a removable top closuremechanically joined to the container body to carry the structural loadsof container and contents, the mechanical joint being cylindrical andconnected and disconnected by rotation of the top closure and thecontainer body relative to each other. The ultimate seal during theshelf-life between filling and initial opening of the container iseffected by a rupturable band adhered over the joint, said band in thelocus of the joint line having a strength in shear less than itsadhesive bond to the container closure and body adjacent the joint line.The closure and body are preferably recessed adjacent the joint line toreceive the band. The band is preferably endless and formed in situ byapplication of band material in liquid condition; a repellent oradhesion inhibiter (preferably an immiscible liquid) may be located inor over the joint line to exclude entrance of the band material into thejoint and provide an equatorial area of weakness for rupture of thesealing band.

6 Claims, 3 Drawing Figures -l i wk 30 il 1 22 L 3/ PATENIED JUL 31 msMETHOD OF SEALING A CONTAINER This application is a divisionalapplication with re spect to my copending application Ser. No. 863,105,filed Oct. 2, 1969, now US. Pat. No. 3,608,772.

This invention relates to an improvement in containers and a method ofmaking them. More particularly this invention relates to containershaving a removable top closure which is, on the'one hand, readily openedmanually without the aid of opening tools or equipment, and, on theother, provides a mechanically strong and thoroughly sealed closurewhereby solid and liquid material may be packaged and maintained atsuitable pressures (either sub-atmospheric or superatmospheric if notsimply atmospheric pressures) during the expected shelf-life of thepackaged contents between the filling of the container and its initialopening by the user.

Both as an element of commercially produced closures for cans, jars, orlike containers, or as a temporary means employed by users for securingthe covers or lids on such containers, it has long been a commonpractice to employ an external adhesively secured band wrapped aroundthe substantially cylindrical wall formed at the joint or line ofjuncture between the closure member and the body of the container. Thus,in a can closure, for example, in which there is simply a frictionalslip joint between the cylindrical wall of the container body and adepending flange of a top closure, it has been commercial practice toover-wrap the joint with a removable band of an adhesive tape orthelike, both to secure the closure member from accidental removal andimprove its seal. Likewise, it is a common expedient for housewives, forexample, to secure the screw top of a can or jar, after opening andreclosing, with a strip of pressure-sensitive tape which is removed toallow ready re-opening of the container. In the quest for readily-openedcontainers, particularly those by which liquid and/or solid materialscan be packaged under super-atmospheric pressures or vacuum or those inwhich the processing of the contents after filling and closing maydevelop substantial internal pressure, the foregoing expedients of usingan external band to effect sealing have not been successful, despitetheir convenience.

It is an object and advantage of this invention to provide a sealed,reclosable closure for cans, jars, and the like which may be readilyopened, the sealing being effected by an externally applied sealingband. It is an advantage of this invention that, during the expectedshelf-life of the packaged contents, and irrespective of whether thecontents are packaged at atmospheric pressures, super-atmosphericpressure, or under partial vacuum, the packaged contents will bethoroughly sealed but, nonetheless, may be manually opened withoutrequiring the aid of opening tools or accessories. Further, such openingand rupturing of the seal may be accomplished substantiallyinstinctively by the user and without the need for unusual operations orinstructions therefor which may be overlooked or not followed by theusers.

Other objects and advantages of this invention will be apparent from thefollowing specification, claims, and drawings, of a preferred embodimentwhich may be substantially modified in whole or part:

may removably close and reclose the can, the can beingeffectively'sealed after filling and until it is initially opened by theuser.

FIG. 2 is an elevation of the preferred embodiment disclosed in FIG. 1.8

FIG. 3 is a cross-section of an alternate form of sealing band which,when applied to a container as illustrated in FIG. 1, may have theexternal appearance shown in FIG. 2.

It is to be understood that in the accompanying drawings the thicknessesand proportions of the several elements shown have been exaggerated forclarity of illustration, and, for the smame purposes, structuraldetails, such as the beading of raw edges of sheet-metal used for cansor lids, for example, have been eliminated.

In essence this invention depends upon separating the functions of theconventional gasketed screw or bayonnet locked top or lids for cans,bottles, jars, and the like of both providing the structural strength ofthe closure to resist mechanical loads on the closure and also sealingthe joint between the closure and the container body by compressing agasketing member located in the joint. Particularly if the contents arepackaged so as to maintain a pressure differential from that of theambient atmosphere or if, after the contents have been packaged, thepackage must be subjected to protional load between the mating thread orlug portions FIG. 1 is an essentially diagrammatic representation incross-scction of the upper portion of a metal can having a bayonnet-typeofjoint for a closure top which of the connection that it becomesextremely difficult to loosen the connection for opening without the aidof an opening device or resorting to such expedients as tapping theclosure to dislodge the connection or heating the closure so as toexpand it without expanding the mating portion of the connection. Byreducing the function of the gasketing member, if one is employed, tothat of simply filling gross gaps or discontinuities in the jointbetween the container closure and body and relying upon an externalsealing band covering the joint, adequate structural strength to resistany normal mechanical load on the container may be obtained withoutfrictional resistance to easy opening.

The problems heretofore inherent in transferring such sealing functionsto an external sealing band have been solved in this invention by thediscovery that various suitable banding materials, inert to the packagedcontents and the ambient atmosphere, may have more than adequatestrength to seal any leakage from the contents through the mechanicaljoint of the closure and the container (or leakage into such contents)and yet are so relatively weak in shear strength that they will rupturein shear rather than break an adjacent adhesive bond to structurallystronger materials, such as the sheet metal, glass, or plasticconventionally used for containers and container closures.

To illustrate the application of this discovery to the invention,reference is made to FIGS. 1 and 2, as follows.

As shown in FIG. 1, a tubular can body 10, for example, is formed ofsuitably plated and lacquered sheet metal and provided with a closableopening or mouth portion 11 of reduced diameter. This mouth portion 11is formed with one or more, usually two or three, internal grooves 12(one is illustrated in dotted lines in FIG. 1) extending downwardly fromthe rim of the mouth and then curving to a gently pitched helicallocation below the rim to provide internal bayonet joint slots orinterrupted threads. The can body is closed with a drawn metal lidhaving a downwardly depending flange 21 forming a gripping portionsubstantially equal in diameter to that of the can body. The flange isreduced in diameter below the gripping portion to provide a gasket seatshoulder 22 and below the shoulder 22, the flange 21 is further reducedin diameter to a sleeve portion 23 which internally fits the can bodymouth 11. The sleeve portion 23 is formed with internal dimples 24 whichform raised bosses which are received in the grooves 12. Externally thesleeve portion 23 carries a gasket ring 25 which is lightly compressedbetween the shoulder 22 and rim of the mouth portion 12 when the lid 20,with the bosses of the dimples 24 received in the grooves 12, is turnedclockwise to draw the lid into the mouth portion 11 of the can body 10.

Manifestly, the depending flange of the closure lid 20 may fitexternally of the mouth portion 11 of the can body 10, in which eventthe gasket 25 will usually be located interiorly of the flange so as tobe engaged between an internal shoulder of the closure lid and the rimof the mouth portion of the can body and a second or alternate gasketmay be located in the external circumferential joint between the rim ofthe sleeve portion of the closure flange 21 and the shoulder between thecan body and its mouth portion 11. The arrangement shown in section inFIG. 1 is generally preferred, however, since it enables a relativelyshallow circumferential channel 26 to be formed between the lower edgeof the gripping portion of the flange 21 and the shoulder between thecan body and its mouth portion 11, locating the external joint linebetween the can body and its closure in the center of the channel 26. Ifthe sleeve portion 23 of the closure fits externally of the mouthportion 11 of the can body, it is preferable to provide a steppedshoulder between the can body and its mouth portion, the upper step ofsuch shoulder receiving either rim of the sleeve portion 23 or a gasketengaged by that rim and the lower step providing the lower side of achannel in which the external joint line is centrally located. Theradial depth of the channel 26 is preferably such as to contain theoutwardly extending ridges of the grooves 12 below the cylindricalsurface defined by the gripping surface of the closure flange 21 and thewall of the can body 10; this allows a cover tape 35, described below,to be flush with that surface. Such a channel depth also usually allowsany portion of the gasket 25 which may be bulged when the closure 20 istightened and drawn into the can by operation of the bayonet lockeffected by the grooves 12 and dimples 24 to be contained within thechannel.

Manifestly, instead of the bayonet lock illustrated as the mechanicalconnection between the can body 10 and closure 20,'the location of thedimple 24 on the sleeve portion 23 and the groove 12 on the mouthportion 11 may be reversed or a coarse screw connection of one or morecontinuous or interrupted threads may be employed. Likewise, while thecontainer body 10 and closure 20 are indicated as being of formed sheetmetal in FIG. 1, manifestly the same container structure and closurestructure may be molded of plastic, glass, ceramics, and/or othersuitable material and the material of the container body need not be thesame as that of the closure.

As indicated above, the gasket 25 is preferably only lightly compressedas the container is closed by turning the closure 20 down on thecontainer body 10; the function of the gasket 25, which may be ofnatural or synthetic rubber or other elastomer, polyethylene, an acrylicthermoplastic (e.g., Barex 210), molded cork, compressible paper orfilm, and the like, is primarily to fill any gross gap in the jointbetween the con tainer closure and body and to take up any play in themechanical connection between these two principal members of thecontainer and secondarily to provide a necessary mass to inhibit gasdiffusion. With any sealing function of the gasket 25 thereby beingotherwise incidental, the mechanical connection between the closure andbody can thereby be designed to be amply strong to withstand mechanicalloads which the container may be expected to encounter while holding thefrictional engagement between the locking elements to minimal loads thatcan be pre-set within close tolerances.

The actual sealing of the contents of a container as described above iseffected by a sealing band 30, after the closure has been connected asdescribed above. The band 30 is preferably of a polymeric film materialwhich is relatively adherent to the material of the can body 10 andclosure 20 or which can be made adherent thereto with appropriateadhesion promoter. It is preferably applied by a roller coater, fountainbrush, narrow knife coater, or masked spray while it is in liquid formso as to cure or be cured in the channel 26 at a sufficient depth tocover the gasket 25 and thereby form itself in situ to an endless band.Suitably plasticized vinyl plastisols, plasticized hot-melt resins, andhigh solids content solvent dispersions or latices of polymericfilm-forming resins, such as epoxy-phenolic, epoxy-urea, andpolybutadiene resins, are examples of the general class of materialswhich may be deposited in liquid form over the joint line between thecontainer closure and body to provide the desired adherent sealing band.

When the adherent sealing band is formed in the channel 26 as definedabove, it is desirable to provide a non-adherent or less adherentequatorial area in the locus of the joint line which will permit readyrupture of the band in shear; this may be accomplished by one of thefollowing means: The materials of the gasket 25 and the band 30 areeither selected to be mutually repellent and immiscible so that there isno significant adhesion between the gasket 25 and band 30 or, prior toapplication of the band, the exposed surface of the gasket is coatedwith a narrow strip of liquid which blocks adhesion of the band to thegasket and which also preferably seeps into any interface between thegasket and the edges of the joint line; if no gasket is provided in theexternal joint line, the joint is filled with such an adhe sion blockingliquid prior to application of the band 30. The composition of theadhesion blocking liquid will necessarily vary according to thecomposition of the band material and the relative repulsion orimmiscibility of them. For example, if the band 30 is formed of arelatively hydrophobic vinyl plastisol, a relatively hydrophilicglycerol or sugar syrup may be employed to block adhesion in the locusof the joint. Alternatively, the sealant band-forming liquid may befonnulated so as to be sufficiently viscous or thixotropic .that it willnot seep into the joint.

As an alternative to the formation of the sealing band 30 in situ, onemay employ heat-sealing tapes, such as a plasticized vinyl tape whichmay be fused to itself and the container elements, provided, of course,that an adhesion block is located in or at the joint line of thecontainer. If preformed films or tapes are used, care must be taken toassure not only that a secure, leak-free vertical seam between thebutted or overlapped ends of the tape is obtained but also that the tapeis well adhered on either side of the joint line while leaving anintermediate unadhered portion of sufficient width over the joint lineto allow shearing forces to develop and rupture the tape as the closureand container body are twisted relatively to each other to open thecontainer.

Due to the reduction in thickness of the band 30 over the gasket 25, dueeither to the bulging of the gasket or the effect of the adhesionblocking liquid, or both, there is thereby provided an internal scoreline 31 for rupture of the sealing band 30 when the band is subjected toshear by turning the closure 21 counterclockwise to open the container.The thickness of the sealing band at the locus of the joint may therebybe closely controlled and effectively pre-set to limit the torquerequired to open a sealed container. Ifthe band 30 is formed from alength of pre-formed tape or film, either an external or internal scoreline may be cut into the tape to control the torque necessary to rupturethe tape and insure that the force necessary to do so will be less thanthe adhesive bond to the container body and closure.

The sealing band 30 may be pigmented, if desired, to provide anattractive ornamentation of the container. However, its surface may berelatively soft and subject to scuffing during shipment and handling. Toso protect the band 30, and provide a printable display surface and, insome cases, for sanitary reasons, a protective band 35 may be employed.The band 35 may be an encircling band of shrinkable cellulose, vinyl, orother shrinkable film, or it may be a strip of paper, tough plastic,metal foil, or a laminate of one or more of these materials; it may beadhered to the sealing band 30 by a pressure-sensitive or like peelableadhesive or may be simply frictionally secured by a tight seam ofadhesive 36 between overlapped ends, as shown in FIG. 2. In any case,the band 35 is preferably provided with a free lifttab 37 to permit itto be stripped readily. The band 35 may also serve an actual scalingfunction, particularly when made of metal foil or a metal foil laminate,by increasing the impermeability of the sealing band 30 as well as byserving as a reinforcement for the polymeric resin of the band 30. Forexample, if the contents of the container are packaged under asubstantial vacuum or under relatively high super-atmospheric pressuresimposed by gaseous contents, such a pressure differential couldeventually rupture the band 30 at one or more points along the line 31unless the sealing band were reinforced by the peelable or shrunk-fitband 35.

While it is preferred to form the sealing band 30 from a polymeric resinin a liquid condition and which may be cured in place over the jointline between the container body and closure,as described above, thisinvention is not limited to use of such sealing band. Particu= larlywhen a prime requisite for the sealing band is its function as a barrieragainst transmission of moisture and like vapors and gases, it may bedesirable to form a band 130 of a metal foil or laminated foil and/orpaper or film. As shown in FIG. 3, the band may be formed of a striphaving marginal portions 132 and 133 folded back on and preferablylaminated to its center portion 131 and either the marginal portions orthe corresponding areas of the center portion 131 are then adhered tothe can body and closure so that the line or space 134 between adjacentedges of the marginal portion overlies the joint line between theclosure and body and is preferably free of adhesive in the locus of thatline. The ends of such a folded band of strip material may be joined bya lapped vertical seam corresponding to the seam 36 shown in FIG. 2 andthe external end may have a lift tab corresponding to the lift tabs 37to rupture the vertical overlapped seam joining the ends of the band.When adjacent adjacnet edges of the marginal portions 132 and 133 arespaced to provide a gap 134 as shown in FIG. 3 and the marginal portionsare adhered to the can body and closure, such a gap is usuallysufficient to receive the bulging of a gasket in the joint and may bemade wide enough to insure that any adhesive forced toward the jointline as the marginal portions are pressed against the container andclosure wall will flow into the gap 134 rather than into the jointbetween the container body and its closure and still leave an unadheredportion overlying the joint line. When the material of the band 130consists of aluminum foil having gauge of 0.0001 to 0.0006 inch, it isusually desirable to protect such relatively soft foil from abrasion byan overlying removable protective band 35.

As in the case of a sealing band 30, a sealing band 131 can haveadequate structural strength to perform its function of sealing themechanical joint between the container body and its closure. Yet, uponthe manual application of torque (within limits which can bepredetermined to close tolerances), the closure and container body canbe readily rotated with respect to each other so as to rupture the bandin shear over the joint line. A relatively clear line of fractureappears to be aided by slight tension placed on the circumferential lineof weakness in the sealing band, which tension is most convenientlyobtained with a mechanical interlock between the closure and containerbody which causes the closure to move helically away from the containerbody as they are rotated with respect to each other.

If this container body 10 is, as shown in the drawings, that of a sheetmetal can having a conventional crimped and sealed bottom closure, theusual practice is to assemble and complete the closing and sealing ofthe top closure according to the invention, inverting the container tofill it with the contents introduced through the open bottom, and thenclosing and sealing the container with the conventional bottom closure.if the container body 10 is that of a conventional jar or bottle whichcan be filled only through an open mouth, this invention permits suchfilling with most contents which can be packaged in such container. If,as in the case of many foodstuffs, the contents to be packaged requireprocessing at high temperature after filling and sealing in order tosterilize or pasturize them, an advantage of this invention is that suchprocessing temperature can also cure or complete the cure of the sealingband so as to adhere it firmly to areas adjacent the joint line of theclosure.

While a sealing band rupturable in shear according to the invention ispreferably received in a circumferential channel in which the joint linebetween the container body and closure is located, it is to beunderstood that such surface configuration adjacent the line may beomitted so that the band will protrude from the surfaces adjacent thejoint line. The rupturable sealing band is usually cylindrical, orsubstantially so, since the joint line between the container body andits closure is usually a circle lying in the perimeter of an areaprovided by adjacent marginal portions of the container body andclosure, which area is essential cylindrical. if the area defined bymarginal portions adjacent the joint line is other than essentiallycylindrical, then, so long as it is essentially the surface of a solidof revolution, a sealing band 130 can usually be shaped to lie over thejoint line while being adhered securely to the adjacent area of thecontainer and closure; an advantage of forming the band 30 in situ is,of course, that it can accommodate itself to extremely irregularsurfaces adjacent the joint line.

Still other modifications and departures from the disclosed specificembodiment of this invention can be made without departing from thescope of the following claims. In the following claims, it is to beunderstood that the term unadhered as applied to the medial portion ofthe sealing band overlying the joint line as an equatorial area betweenthe adherent marginal portions includes the modification of causing orallowing such circumferential area to be more weakly adhered than, andthus relatively unadhered with respect to, the more strongly adheredmarginal portions. in this connection, so far as it is understood, afunction of such unadhered (or less strongly adhered) circumferentialmedial area of the sealing band appears to be that of allowing shearingstrains, adequate to rupture the band, to develop upon rotation of onemarginal portion of the band with respect to the other. It has also beenobserved that, within the limits of a sealing band of a material andthickness in its circumferential medial area capable of being rupturedin that area due to torque applied to the marginal portion which remainsadhered, if resistance to rupture in the medial circumferential area ofthe sealing band exceeds that which is convenient for manual applicationof such torque, such resistance may usually be decreased by increasingthe axial width of the circumferential area; similarly, if suchresistance to rupture is less than that desired, it may be increased bydecreasing the width of the medial unadhered portion.

What is claimed is:

l. A method of sealing a container comprised of a body having a mouthportion with a substantially circular edge and closed by a closureinterfitting said mouth portion to provide a circular outer joint linecomprising the steps of locating a sealing band over said joint line andcircumferential areas of said closure and said mouth portion adjacentsaid joint line and adhering said band to said marginal circumferentialareas with adhesive bonds stronger than the shear strength of said bandwhile avoiding such adhesion of a medial portion of said band at saidjoint line.

2. A method as defined in claim 1 including the step of filling saidjoint line with a repellant to adhesion to said sealing band prior tolocating said sealing band over said joint line.

3. A method as defined in claim 2 including the step of forming saidsealing band in situ by applying a polymeric resinous liquid coatingover said joint and adjacent marginal circumferential areas and curingsaid coating to a solid condition to adhere the same to saidcircumferential areas but without adhesion at said joint line.

4. A method as defined in claim 3 including the step of reinforcing saidsealing band with an overlying band of flexible but relatively inelasticsheet material, of the class consisting of metal foil, organic film,paper, and laminates thereof.

5. A method as defined in claim 1 in which said sealing band iscomprised of a strip of flexible sheet material of the class consistingof metal foil, organic film, paper, and laminates thereof and includingthe step of joining the ends of said strip with a transverse overlappedseam to form and locate said band.

6. A method as defined in claim 5 including thestep of first foldingmarginal portions of said strip toward the longitudinal center thereofand joining the same to the unfolded portion of said strip to provide astrip having marginal portions of greater shear strength than the medialportion thereof.

1. A method of sealing a container comprised of a body having a mouthportion with a substantially circular edge and closed by a closureinterfitting said mouth portion to provide a circular outer joint linecomprising the steps of locating a sealing band over said joint line andcircumferential areas of said closure and said mouth portion adjacentsaid joint line and adhering said band to said marginal circumferentialareas with adhesive bonds stronger than the shear strength of said bandwhile avoiding such adhesion of a medial portion of said band at saidjoint line.
 2. A method as defined in claim 1 including the step offilling said joint line with a repellant to adhesion to said sealingband prior to locating said sealing band over said joint line.
 3. Amethod as defined in claim 2 including the step of forming said sealingband in situ by applying a polymeric resinous liquid coating over saidjoint and adjacent marginal circumferential areas and curing saidcoating to a solid condition to adhere the same to said circumferentialareas but without adhesion at said joint line.
 4. A method as defined inclaim 3 including the step of reinforcing said sealing band with anoverlying band of flexible but relatively inelastic sheet material ofthe class consisting of metal foil, organic film, paper, and laminatesthereof.
 5. A method as defined in claim 1 in which said sealing band iscomprised of a strip of flexible sheet material of the class consistingof metal foil, organic film, paper, and laminates thereof and includingthe step of joining the ends of said strip with a transverse overlappedseam to form and locate said band.
 6. A method as defined in claim 5including the step of first folding marginal portions of said striptoward the longitudinal center thereof and joining the same to theunfolded portion of said strip to provide a strip having marginalportions of greater shear strength than the medial portion thereof.